Children get fatter the more time their mothers spend at work, research has suggested.

The Scottish government study said part of the reason could be because busy mums may serve up more ready meals and fast food.

The Millennium Cohort study found that seven-year-olds whose mums worked were less likely to be obese than others.

But the risk of becoming overweight grows with the number of hours mums spend at work.

The report said: "An increasing number of hours of maternal employment per week was associated with an increased prevalence of overweight and obesity at age seven."

The researchers said this was a particular worry for kids from well-off households.

The study, which looked at 13,800 families, stressed there were other, more significant, factors affecting childhood obesity. They include birth weight and having parents who are overweight or who smoke.

In the UK, 23 per cent of seven-year-olds are overweight and 11 per cent are obese.